1. Field of the Invention
The present invention relates generally to a switchgear assembly for an electrical apparatus, and more particularly, to a switchgear assembly such as a disconnecting switch assembly, a fuse assembly and the like for opening and closing an electrical circuit connecting between a power source and an electrical load such as an electrical machine or apparatus.
2. Description of the Prior Art
In general, in order to disconnect an electrical machine or apparatus from a power source as required, a switchgear assembly is provided between the electrical machine or apparatus and the power source. FIG. 5 shows an example of the construction and arrangement of such a conventional switchgear assembly. In FIG. 5, fixedly mounted on a base 1 is a vertical pole 2 on the top of which a bus bar 4 of copper wires is supported through a support insulator 3. The bus bar 4 is attached to the support insulator 3 by means of a fastening member 3a at right angles relative to the support insulator 3 and the pole 2. Provided on the upper portion of the pole 2 is a switchgear in the from of a disconnecting switch assembly, generally designated at reference numeral 5, which includes a pair of support insulators 7 and 9 disposed horizontally in vertically spaced parallel relation with each other and fixedly mounted at their base end through a common support member 10 on the pole 2. The upper support insulator 7 has a fixed contact 6 attached to the distal end thereof, and the lower support insulator 9 has a support terminal 8 firmly secured to the distal end thereof with a movable contact 11 pivotally mounted at its lower end as at 11b on the support terminal 8 for rotary movement on a vertical plane. The movable contact 11 is integrally formed near the upper end thereof with an engagement eye 11a and is adapted to be engageable at its upper end with the fixed contact 6, the vertical distance between the upper and lower support insulators 7 and 9 and the length of the movable contact 11 being determined such that the upper end of the movable contact 11 can engage the fixed contact 6 at its vertical or upright position as illustrated by the solid outline of the movable contact 11 in FIG. 5. Thus, the disconnecting switch 5 is fixedly mounted through the support member 10 on the pole 2 with the upper support insulator 7 being disposed substantially at right angles relative to the vertically disposed support insulator 3. The fixed contact 6 of the disconnecting switch 5 is connected with a terminal member 12b which in turn is connected through a flexible conductor 12 to a terminal member 12a attached to the bus bar 4. On the other hand, attached to the support terminal 8 on the lower support insulator 9 is a terminal member 13a which is connected via a flexible conductor 13 to an electrical apparatus (not shown).
With the disconnecting switch 5 as constructed and arranged in the above-described manner, when the electrical apparatus is to be diconnected from the power source, one engages a hook of an electrically insulated manipulative rod (not shown) with the engagement eye 11a of the movable contact 11 and then pulls the upper end of the movable contact 11 rightwards as viewed in FIG. 5, whereby the movable contact 11 is disengaged from the fixed contact 6 and caused to rotate around the pivot point 11b in a clockwise direction in FIG. 5 toward a downwardly inclined position as illustrated by the phantom outline of the contact 11 in FIG. 5. As a result, a load-side electrical circuit constituted by the lower support terminal 8 and the flexible conductor 13 is electrically disconnected or separated from the power-source-side electrical circuit constituted by the bus bar 4 of copper wires, the flexible conductor 12 and the fixed contact 6 so that electrical equipment connected with the flexible conductor 13 is disconnected from the power source.
With the conventional disconnecting switch assembly 5 as constructed in the above-described manner, there has been a problem in that if the disconnecting switch 5 is applied to a mobile substation or a small-sized substation, the distance between the base 1 and the bus bar 4 must be decreased to a certain extent due to the dimensional restrictions required for transportation etc., so that operability and safety of the diconnecting switch are considerably impaired. In addition, there are contradictory problems in that a certain clearance is required for satisfactory manipulation of the disconnecting switch, but on the other hand, in order to minimize spacing between mutually adjacent devices disposed below the disconnecting switch assembly as much as possible for reducing the overall installation area and/or space for such devices, it is necessary to arrange the disconnecting switch assembly at a location as high as possible.
The same problems have been involved in the case of a switchgear in the form of a fuse assembly as illustrated in FIG. 6. In FIG. 6, parts or elements corresponding to those shown in FIG. 5 are identified by the same reference numerals. In this Figure, the fuse assembly, generally designated at reference numeral 5', includes a cylindrical fuse 11' containing therein a fuse element (not shown) and disposed between an upper retainer 6' attached to the distal end of an upper support insulator 7 and a lower retainer 8' attached to the distal end of a lower support insulator 9. The cylindrical fuse 11' having an engagement eye 11a' is releasably engageable at its upper end with the upper retainer 6' and at its lower end with the lower retainer 8'. The lower end of the cylindrical fuse 11' is pivoted to the lower retainer 8' for rotary movement on a vertical plane. With this arrangement, when excessive current flows from the bus bar 4 to the electrical apparatus connected with the flexible conductor 13, the fuse element (not shown) in the cylindrical fuse 11' is blown out so that the electrical apparatus is disconnected from the power source. In this case, one engages a hook of an electrically insulated manipulative rod (not shown) with the engagement eye 11a of the fuse 11' and then pulls the upper end of the fuse 11' rightwards as viewed in FIG. 6, whereby the fuse 11' is disengaged from the upper retainer 6' and caused to rotate around the pivot point 11b' in a clockwise direction as illustrated by the broken line in FIG. 6. As a result, a load-side electrical circuit constituted by the lower bracker 8' and the flexible conductor 13 is electrically disconnected or separated from the power-source-side electrical circuit constituted by the bus bar 4 of copper wires, the flexible conductor 12 and the upper retainer 6' so that the electrical apparatus connected with the flexible conductor 13 is disconnected from the power source. Thereafter, the load-side electrical circuit is checked and the failed fuse 11' is replaced with a new one.